Answer:
The Intergovernmental Panel on Climate Change’s Fifth Assessment Report (AR5), which is the most comprehensive and relevant analysis of climate change, concludes that hundreds of millions of people will be affected by climate change. Its consequences will be felt directly and indirectly via resource availability and population movements, spreading consequences across the globe.
For this reason, the EU’s foreign and security policies, as well as official publications and strategies, have devoted increasing attention to climate-related factors. For instance, the joint report by Javier Solana and the European Commission defines climate change as a ‘threat’ multiplier, as it could be responsible for political and security risks affecting European interests (European Council 2008). Environmentally induced migration is quoted among the various threats identified in the report. According to the Council Conclusions on EU Climate Diplomacy, adopted in June 2011, climate change is a global environmental and development challenge with significant implications related to security and migratory pressures (European Council 2011).
The idea that climate-related migration could generate repercussions for European security is related to the possibility of large inflows of people from the areas adversely affected by climate change. Predictions of these flows, however, are extremely imprecise and based on a very wide range of hypotheses. The number of predicted migrants range wildly from 25 million to one billion over the next 40 years (IOM 2009). Vulnerability to climate change in poor countries, while certainly increasing the incentive to migrate, does not necessarily imply that migration will occur. Climate change, by decreasing the available resources, may constrain the ability to emigrate, and some vulnerable individuals may find themselves less mobile and less likely to migrate (Barrett 2008, Cattaneo and Massetti 2015, Gray and Mueller 2012, Foresight 2011).
New research
In a recent paper (Cattaneo and Peri 2015), we tackle the connection between increasing temperatures and migration by analysing the effect of differential warming trends across countries on the probability of migrating out of the country or migrating from rural to urban areas. A crucial insight is that by impoverishing rural populations and worsening their income perspectives, long-term warming affects migration in different ways, depending on the initial income of those rural populations. A decline in agricultural productivity, causing a decline in rural income, seems to have a depressing effect on the possibility of emigrating in extremely poor countries where individuals live on subsistence income. Lower income worsens their liquidity constraint, implying that potential migrants have a reduced ability to pay for migration costs and to afford travel and relocation costs. In this case, global warming may trap rural populations in local poverty. In contrast, in countries where individuals are not extremely poor, a decline in agricultural income strengthens the incentives to migrate to cities or abroad. Decreasing agricultural productivity may encourage a mechanism that ultimately leads to economic success of migrants, benefitting their country of origin and shifting people out of agriculture into urban environments.
Figure 1 provides correlations that corroborate this insight. The figure plots long-term changes (between 1960 and 2000) in temperature (horizontal axis) against long-term changes in emigration rates for poor countries (Panel 2) and for middle-income countries (Panel 1). The difference in the relationship between the two groups of countries is clear. Middle-income countries show a (small) positive correlation while poor countries show a negative correlation between temperature and emigration rate changes.
Figure 1. Change in emigration rates and in average temperature
Step-by-step explanation: